1.3.2 ICMP

<Structure of this section>

(1) ICMP messaging format

The formats and settings of ICMP messages sent by the Switch conform to RFC792,RFC950, and RFC1122.

(2) ICMP messaging support spec

The following table describes the supported ICMP message types.

Table 1-3 ICMP Message Supported Specifications (decimal)
ICMP message				Supported
Type		Detailed type
-	Code	-	Code
Destination Unreachable	3	Net Unreachable	0	OK
		Host Unreachable	1	OK
		Protocol Unreachable	2	OK
		Port Unreachable	3	OK
		Fragmentation Needed and DF Set	4	OK
		Source Route Failed	5	OK
		Destination Network Unknown	6	NG
		Destination Host Unknown	7	NG
		Network Unreachable for Type of Service	11	NG
		Host Unreachable for Type of Service	12	NG
		Communication Administratively Prohibited	13	OK
		Host Precedence Violation	14	NG
		Precedence Cutoff in Effect	15	NG
Source Quench	4	-	0	NG
Redirect	5	Redirect Datagrams for the Network	0	NG
		Redirect Datagrams for the Host	1	OK
		Redirect Datagrams for the Type of Service and Network	2	NG
		Redirect Datagrams for the Type of Service and Host	3	NG
Time Exceeded	11	Time to Live Exceeded in Transit	0	OK
Time Exceeded	11	Fragment Reassembly Time Exceeded	1	NG
Parameter Problem	12	Pointer Indicates the Error	0	OK
		Missing a Required	1	NG
		Bad Length	2	NG
Echo Request	8	-	0	OK
Echo Reply	0	-	0	OK
Timestamp Request	13	-	0	NG
Timestamp Reply	14	-	0	OK^#
Information Request	15	-	0	NG
Information Reply	16	-	0	NG
Address Mask Request	17	-	0	NG
Address Mask Reply	18	-	0	OK^#
Router Advertisement Message	9	Normal Router Advertisement	0	NG
Router Solicitation Message	10	-	-	NG

Legend: OK: Supported NG: Not supported-: Not applicable

#: When a Request message is received, a Reply message is returned.

(3) ICMP Redirect Send Specifications

When the receiving interface and the sending interface are the same for a forwarded packet, the hardware determines that a decision about whether an ICMP Redirect message can be sent is required, and the software determines whether an ICMP Redirect message can be sent. The software sends an ICMP Redirect message when the following conditions are met:

The packet source and the next hop router belong to the same segment (the subnetwork address in the source IP address of the received IP packet matches the subnetwork address of the next hop router to which the IP packet is to be forwarded).

An exception is a subnetwork address in the received IP packet that matches the default route.
The received IP packet is not an ICMP packet.
Sending is enabled in the IP routing information in the configuration.

(4) ICMP Time Exceeded Send Specifications

The switch sends an ICMP Time Exceeded message when the following conditions are met:

The TTL is 1 in the received IP packet to be forwarded.
The received IP packet is not an ICMP packet (ICMP Echo packets excepted).